Introduction
The growth of Thermophilic bacteria increases during the process of manufacturing milk powder (Murphy 42-50). There is no health hazard posed by the Thermophilic bacteria responsible for the formation of spores. Nevertheless, when milk powder contains them in numerous numbers, it does not only point to poor methods of manufacturing, but can also result in deterioration of the product’s enzymes. This may lead to changes in both organoleptic properties and the composition of the product. Thus, during the manufacture of milk powder, it is important to carry out a test for Thermophilic bacteria (Flint Para.5). This essay is a description of the use of the BactiFlow system to develop a rapid test for Thermophilic bacteria. Thermophilic bacteria refers to the bacteria whose optimum temperature of growth is about 55° C.
Materials and method
Protocol T is the test method used. Its basis is the milk powder protocol which is useful in enumerating all bacteria present in milk powder. The protocol was modified in four ways to be able to particularly detect Thermophilic bacteria. The first modification entailed heat treatment of the sample for 10 minutes at a temperature of about 62.8°C. The heat treatment was based on the fact that the heat tolerance for mesophilic bacilli is less than that of thermophilic bacilli. Second, the protocol was modified by raising the temperature required for labeling the bacterial cells. “The third modification was the addition of 0·8% ethylenediaminetetraacetic acid (EDTA) to the A31 buffer (Chemunex SA) used in the pretreatment of milk powder reconstituted in 0·1% peptone” (Flint para.13). Hydrolysis of the substrate used will occur at temperatures above 30°C. After being hydrolyzed, it links itself to the casein micelles found in milk powder that’s reconstituted. This makes the test unreadable due to the BackFlow’s high background readings. Casein micelles are dissociated by EDTA (Ward 495-504).
The fourth modification was that the Chemunex CSR reagent was optimized. This was done to minimize the sample’s nonspecific labeling. A vortex mixer rather than gentle mixing was used to mix the sample with the reagent. This did not only minimize background staining but also ensured that the contact between the test solution and the reagent was rapid.
Validation
Different milk powders were obtained from several dairy manufacturing plants in New Zealand. “These were dissolved in 0·1% peptone (10% w/v) and mixed in a peristaltic blender” (Flint para.17). To come up with numerous thermophilic bacteria required for validation, there was the incubation of milk powders at 55° C for about two to three hours. During validation, 36 samples of fresh milk powder were tested in triplicate to find the total count of thermophilic bacteria present in them.
Uses, Advantages and Limitations
Results from this test are applicable in effectively detecting problems, being able to monitor the process of manufacturing and instilling confidence in the manufacture of dairy products. “The key advantage of protocol T over the standard agar plating method is the ability to take action on results obtained within 1–2 h compared with 48 h for the plate count assay” (Flint Para.33). On the other hand, a possible shortcoming of protocol T is that mesophilic spores present in the milk powder can be labeled during the step of pre-treatment.
Conclusion
The BactiFlow cytometer can be used to enumerate thermophilic bacteria in milk powder within one hour.
Works Cited
Flint, Steve, et al. Description and validation of a rapid (1 h) flow cytometry test for Enumerating thermophilic bacteria in milk powders. Journal of Applied microbiology. Volume 102 (4), 2006.
Murphy, Patrick, et al. Growth of thermophilic spore forming bacilli in milk during the manufacture of low heat powders. International Journal of Dairy Technology Volume 52 (2), 1999.
Ward, Brent, et al. EDTA-induced dissociation of casein micelles and its effect on foaming properties of milk. Journal of Dairy Research. Volume 64 (4), 1997.